
Smith, Kline 6 French Company 

Philadelphia 




























Observations 

\ 

on 

Milk Coagulation 

and 

Digestion 


By Franklin W. White, M. D. 
BOSTON, MASS. 


REPRINT FROM THE 

Journal Boston Society of Medical Sciences 

December 4, 1900 


Compliments of 

Smith, Kline & French Company 

Philadelphia 















TNT EXCHA NGF 
F.w. Putnam 





Observations on MilK 
Coagulation and Digestion 


T HE proteid element in cow’s milk is the 
portion most likely to cause trouble in 
infants and other persons whose digestive 
powers are feeble. Various methods have been 
used to render it more digestible, such as diluting 
or peptonizing the milk or the addition of mucil¬ 
aginous substances to render the milk curd finer 
and softer, that it may be more readily broken up, 
and expose a larger surface to the action of the 
digestive fluids,and also render the passage through 
the pylorus more easy. 

This last method is the one we shall consider, 
and usually consists of diluting the milk with 
decoctions of cereals, such as oats, barley or wheat.f 
Our observations have been made to determine : 
First, whether or not these cereal decoctions render 
the milk curd more fine and soft than a simple 
dilution with water. Second, whether one cereal 
is better than another for this purpose. Third, 
whether or not the property of yielding a fine curd 
is wholly due to the starch in solution, and if so, 
what per cent, of starch is desirable ? Fourth, to test 
the value of certain modifications of the methods 
which have been recommended, Fifth, to deter¬ 
mine the effect of lime water and albumen water 
upon the casein curd. 

The method is an old one and the clinicians, 
especially the pediatrists, have always been more 

fThese are the cereals used in Fskay’s Albumenized Food. 


3 







interested in the results than the chemists, and 
have written more about it. 

Huebner, Jacobi, Starr and others believe that 
cereal decoctions mixed with milk have the power 
of getting between the particles of curd mechan¬ 
ically during coagulation, and preventing their 
running together and forming a large compact 
mass. Chapin, after careful experiments in test 
tubes and on dogs, came to the same conclusion. 
He believes that the particles of cellulose, the 
ground up cell-wall of the cereals suspended in 
the fluid, have also an important mechanical action 
on the coagulum. 

Chapin, Starr and J. L,. Smith recommend that 
the starch should be dextrinized by the action of 
diastase, as this makes the starch more digestible 
and still preserves, or even increases, according to 
Chapin, its action on the curd. On the other hand, 
Rotch and Harrington, from experiments in test 
tubes, conclude that the size of the curd depends 
on the degree of the dilution of the milk rather 
than on any special property of the diluent; that 
barley water shows only a fractional difference from 
water, and that until more is known about the 
matter plain water is the most practical and efficient 
diluent. Holt and Biedert also question whether 
anything more is accomplished by dilution with 
cereal gruels than with water. The practical 
importance of this method of feeding infants and 
sick persons, and the difference in opinion as to its 
value render it a fit subject for further study. The 
following experiments were begun at the sugges¬ 
tion of Dr. T. M. Rotch, of Boston : 

The coagulation of milk was first studied outside 
of the body in test tubes, and the results confirmed 
later by animal experiments. In the experiments 


4 


ill test tubes, the conditions which exist in the 
stomach were simulated as far as possible. The 
milk was kept at body temperature and was coagu¬ 
lated by rennet or dilute hydrochloric acid, or a 
mixture of the two, the amount of acid present 
being from 0.2 to 0.3 per cent, which is the acidity 
of the normal stomach of adults. The milk was 
gently agitated during the formation of the curd 
by inverting the test tube slowly a half-dozen 
times. The milk was mixed with an equal part of 
the diluent and 50 Cc. of the mixture used in each 
case. As the coagulation of casein by rennet is 
somewhat different from its precipitation by dilute 
acids, a double series of observations were made. 
To one specimen of milk mixture, 2 or 3 Cc. of an 
active solution of rennet were added. And to 
another, 1 to 1^ Cc. of a 10 per cent, solution of 
HC 1 ; an excess of HC 1 was avoided, in order not 
to redissolve the precipitated casein. The coagu¬ 
lation always took place completely within a half 
minute with both acid and rennet. After noting 
the size and character of the curd, it was usually 
shaken moderately for a moment to determine 
whether it was soft and easily broken up, or tough 
and tenacious. The cereal decoctions were made 
from barley, oats, rice and wheat, parti) 7 from 
the grains themselves and partly from cereal flours; 
two tablespoons of cereal grains, soaked over night 
in water, were boiled for several hours in a quart 
of water, keeping the quantity up to a quart by the 
addition of water, and strained through coarse 
muslin; or two tablespoons of cereal flours were 
boiled for fifteen or twenty minutes in a quart of 
water. The decoctions obtained by these two 
methods are practically the same in character and 
action, and after the first few experiments the 


5 


cereal flours were used entirely, for the sake of 
convenience. The decoctions were freshly prepared 
for each series of observations, and a portion was 
dextrinized for from fifteen to twenty minutes with 
Taka-diastase (o.i Gm. in 200 Cc.) before mixture 
with the milk. 

An analysis of four specimens of barley water 
gave an average of 1.5 per cent, of starch. A com¬ 
plete analysis of one specimen of barley water 
gave the following results : 


Starch. 1.56 

Fat. 0.05 

Proteid. 0.25 

Salts. 0.03 

Water.98.11 


100.00 


This analysis shows that the starch is the 
only element of importance in the solution, 
the others being too small in amount to have 
any effect. In our experiments, the milk diluted 
with 1 y 2 percent, starch solution contained approxi¬ 
mately seven-tenths per cent. In the first series 
of experiments, a comparison was made with milk 
diluted with equal parts of : (1) Water ; (2) Barley 
water ; (3) Barley flour water ; (4) Barley flour water 
dextrinized. 

Coagulation was produced by : (A) Rennet; (B) 
HC 1 ; (C) a mixture of rennet and HC 1 . 

The second series was a repetition of the first. 
In the third series a comparison was made between 
milk diluted with equal parts of the following : 


(1) Water 

(2) Barley water 

(3) Oatmeal “ 

(4) Rice “ 

(5) Wheat 


(6) Barley water dextrinized 

(7) Oat 

(8) Rice 

(9) Wheat 


6 








The fourth series is a repetition of the third 
series. 

The results were as follows: Milk and cereal 
water in the strength used always yielded much 
finer curds tha?i milk and water * The curds in 
the first place being soft, firm and flocculent; 
and in the second, large, tough and cheesy. 
There was no qualitative difference in the action 
of HC 1 or rennet as a precipitant. There was no 
difference in the action of cereal waters made from 
the grains or from flours; there was no practical 
difference in the action of different kinds of gruels 
when made in the same strength. 

The dextrinized gruels in three instances gave 
the same results as the plain gruels ; in seventeen 
instances yielded a coarser and tougher curd, in 
four of the latter having no more action than 
water, and in thirteen being intermediate between 
water and plain gruel. This variation is due, I 
think, to the different degrees of action of diastase 
on the starch, the more complete the malting, 
the less the effect upon the curd. The results 
from test tube experiments were briefly — that 
cereal water was much better than water for our 
purpose , and dextrinized cereal water intermediate 
between the two. The next step was to test these 
results in the animal stomach. Cats and dogs were 
used for the experiments, being fed with the same 
mixtures as were used in the test tube experiments, 
then killed one-half hour later and the stomach 
contents removed and examined. The results were 
as follows: The difference between the action 
of barley water and water as diluents was 
more striking, if anything, in the stomach 


*See cut on Page 12. 


7 



than in test tubes. f Where water was used, the 
casein was, for the most part, gathered in one or 
more solid rounded masses surrounded by rather 
clear whey. Where barley water was used, it was 
in the form of soft flakes, evenly distributed. 
Where dextrinized barley water was used, 
the curd was much coarser and tougher than 
with plain barley water, and approached 
closely the curd yielded by milk and water. 



STOMACH CONTENTS. 

MILK AND WATER. 

Several of the milk and barley water mixtures 
were heated to i 67°F. for one-half hour, as is ordi- 


fSee cut above (which accompanied Dr. White’s origi¬ 
nal article). 


8 





narily done in the pasteurizing of milk, to deter¬ 
mine the effect. It was found that there was little 
difference between heated and unheated milk, 
but , if anything , the action upon the curd was 
slightly improved by heating the milk and barley 
water together in this way. Now, that we have 
clearly proved the action of barley water in reducing 
the size and tenacity of the milk curd, we must 
ask for an explanation of this effect. 

I believe that it is mainly, if not wholly, due 
to the starch that is in solution ; starch , in 
common with all colloidal substances, possesses the 
physical property of forming fine emulsions , which 
is analogous to its action in getting between the 
particles of casein curd and preventing their uniting 
into a firm mass. This will explain also the vari¬ 
able action of the dextrinized barley water. The 
starch was rapidly converted under the influence 
of an active ferment to dextrin and then to crys¬ 
talline maltose, which presumably had no effect 
on the curd, and the greater the degree of con = 
version in any specimen, the less its effect on 
the casein. This view was confirmed by the fol¬ 
lowing experiment: 

A specimen of 300 Cc. barley water was dextrin¬ 
ized with 0.2 Gm. taka-diastase; samples were 
removed at the start and at intervals of fifteen min¬ 
utes for an hour, and mixed with an equal amount 
of milk. The milk was coagulated immediately 
after the mixture, one portion with HC 1 and one 
portion with rennet. 

The milk mixture containing barley water , 
which had been dextrinized por fifteen minutes , 
yielded a decidedly coarser curd than milk and 
plain barley water. Those containing barley 
water , which had been dextrinized for thirty min- 


.9 


utes or longer , yielded a curd of the same character 
as produced in milk and water. In short, instead 
of preserving or improving the actio?i of barley 
water by converting the starch , as claimed by 
Chapin, we find that its action is speedily lost if 
the ferment is an active one. This experiment 
also disposes of the idea that cellulose in suspension 
or calcium salts in solution derived from barley 
have any important action on the curd, for the 
properties of the fluid were lost when the starch 
was removed ; even though cellulose and salts were 
left. It was also found that a boiled and strained 
solution of corn starch , in which there is relatively 
little cellulose, gave the same result in milk mix¬ 
tures as a barley water containing a 7 i equal per 
cent, of starch. 

Experiments showed that from T % to i t 5 q per 
cent, of starch was best for practical results; less 
than t 7 o gives much coarser curds, and this explains 
the variety of opinions which have been held of 
the value of barley water as a diluent of milk. 
Those who found it without effect, used too dilute 
a preparation.* 

Albumen water mixed wfith milk, for the purpose 
of preventing large tough curds, is'not practicable, 
for two reasons: First, it has no effect on the curd 
in i per cent, or if per cent, solutions, which are 
the strongest that can be used without giving too 
much proteid. Second, the mixture could not be 
pasteurized without coagulating a considerable 
amount of proteid. 

A few additional observations were made on the 
effect of adding lime water to milk. The experi- 

*Ttae amount of starch in Eskay’s Albumenized Food, when prepared 
for administration, is from 1 to \% per cent., which is within the 
limits giving the best results according to Doctor White. 


io 


ments showed that the addition of lime water to 
milk simply prevents the action of rennet until the 
alkali is neutralized by the secretion of HCl in the 
stomach , but does not affect the character of the 
curd which is then formed. Probably the only 
effect of the small amount of lime water, usually 
added to milk in infant feeding, is to neutralize 
some of the lactic acid which may be developed 
in it. 

The practical importance of using cereal decoc¬ 
tions as diluents of milk is so obvious that I shall 
do no more than mention it. Milk is one of the 
most important of food-stuffs ; it is the exclusive 
food for infants, the basis of the diet of older 
children, and is commonly used by adults where 
digestion is impaired from whatever cause, as in 
fevers, diseases of the stomach and intestines, and 
nephritis, and any method which can increase its 
digestibility has a wide practical application. 
Surely, every physician who has to feed an infant 
upon cow's milk with its j per cent, of casein in 
place of human milk with ]/ 2 perc ent. op casein, 
willf ully appreciate any method which will render 
thecoagulum more digestible. The conclusions from 
my observations may be summarized as follows : 

1. Dilution of milk with cereal decoctions op 
proper strength renders the casein curd much 
more fine , soft and digestible than simple dilution 
with w&ter .* There is no difference in the action 
of various cereals, such as barley, oats, rice or 
wheat. 

2. The above property is due mainly , if not 
wholly , to the starch in solution , the most desirable 


* When the cow’s milk is modified by the addition of 
Eskay’s Albumenized Food the formation of tough curds is 
entirely prevented. See cut at end of this article, page 12. 




amount of starch in the milk mixture for practical 
use is approximately three-fourths per cent. 

3. Diastase , by converting the starch to dex¬ 
trine and maltose , promptly lessens and removes 
the action of cereal waters upon casein. Its addi¬ 
tion, therefore, is not a practical measure when 
the action upon the curd is desired. 

4. Albumen water has no practical value as a 
diluent of milk. 

5. Lime ivater added to milk has no more effect 
than water upon the character of the curd pro¬ 
duced in the animal stomach. 



Gastric contents of a child fed upon cows milk 
MODIFIED BY ESKAY’S ALBUM ENI 2 ED FOOD SIPHONED 

OFF ONE HOUR AFTER TAKING THE FOOD. 

Note smooth flocculent appearance. 


12 










































































